Preparation And Dye Degradation Performance Of Modified TiO₂ Based Catalyst

Printing and dyeing wastewater is an important part of industrial wastewater.Because printing and dyeing wastewater has different colors,complex composition and it is difficult to biodegrade,conventional treatment methods have their own shortcomings.The photocatalytic technology has low selectivity to degradants,and the catalyst can be recycled,which can reduce secondary pollution to the environment.It is a wastewater treatment technology that meets the green development concept and has promising prospects.TiO₂ is one of the most popular photocatalysts,but TiO₂ is poor absorption of visible light and poor self-adsorption properties,the generated electron-hole pairs are easy to recombine,and TiO₂ is easy to agglomerate.In this paper,TiO₂ is modified to improve the catalyst performance.The details are as follows:The modified catalyst was prepared by sol-gel method.Non-metal ions F?S and metal ions In are used to dope TiO₂ in different combinations,and the effects of three S sources are considered that are Na₂S·9H₂O,Na₂S₂O₃·5H₂O and H₂NCSNH₂,Rhodamine B as a simulated pollutant,the activity of the catalyst was evaluated according to the removal rate of rhodamine B,the final results show that the F,S?Na₂S·9H₂O?and In co-doped TiO₂ modified catalyst has the best activity and its activity is 13.5 times of pure TiO₂.Combined with SEM,XRD,FT-IR,XPS,UV-Vis,it is found that there is a synergistic effect by three ions co-doped,the particle size of TiO₂ is reduced,and the anatase-type and rutile-type mixed crystal form appears.In view of the poor adsorption performance of the modified catalyst,it is modified by carrier SiO₂,and the modified composite catalyst has good adsorption performance and photocatalytic activity.The analysis shows that the S-doped TiO₂/SiO₂ and calcination temperature have great influence on the adsorption performance of the modified composite catalyst.Combined with the characterization,due to the synergistic effect of the three ions of F?S?In and SiO₂,it is found that the proportion of Ti³⁺than Ti⁴⁺is larger in the modified composite catalyst,and the proportion of F doped into the TiO₂ lattice is larger than F species that adsorbed on the surface of TiO₂.After the preparation conditions of the modified composite catalyst are optimized,the application conditions of the modified composite catalyst are investigated.such as substrate concentration,pH value,dye type and Catalyst dosage.The final results show that the alkaline conditions have great destructive properties on the adsorption performance and activity of the catalyst,and the catalyst has applicability to various dyes.Finally,the stability of the modified catalyst and the modified composite catalyst were investigated.After the two catalysts were recycled for 5 times,the removal rate of Rhodamine B by the two catalysts still did not decrease significantly,showing good stability.In summary,the prepared modified composite catalyst has good photocat alytic activity,adsorption and stability,and provides an important reference for the industrial application of photocatalytic degradation of dyes.